(1) Field of the Invention
This invention relates to a seated-operator type tractor with a vehicle proper and a scraper; which vehicle is equipped, rearwardly thereof, with a link mechanism that is adopted for implement connection and that is raised and lowered by means of oilhydraulic type lift arms; and which scraper, that is for ground-leveling and that may be of a structure even as simple as substantially a blade, is connected to the link mechanism and is adapted to be subjected to rolling-adjustment by means of an oilhydraulic actuator and to have blade angles as are adjustable by means of another oilhydraulic actuator.
(2) Description of the Prior Art
With a tractor equipped with a scraper for ground-leveling, of the structure as above, the ground-leveling work using the scraper has conventionally been difficult in its maneuvering and has required skill in a considerable degree, in view that it has been prevailing to control the oilhydraulic actuator for the adjustment with respect to rolling and the oilhydraulic actuator for the blade-angle adjustment, with respect to their actuation, respectively by means of manual type 3-position controling valves, therefore in order to adjust the working position and posture of the scraper and additionally thereto to maneuver, in raising and lowering, the lift arms, three kinds of manual maneuvering have thus been imposed on the operator who must of course operate and steer the vehicle as well. Especially, level-finishing has been the most difficult step, such that even a skilled operator must repeat the treatment four or five times in order to attain the results satisfactory enough, thus requiring considerable time in such finishing step which has therefore been the one hampering enhancement of the working efficiency.